Memory Arrays Comprising Strings Of Memory Cells And Methods Used In Forming A Memory Array Comprising Strings Of Memory Cells

ABSTRACT

A memory array comprising strings of memory cells comprises laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers. Channel-material-string structures of memory cells extend through the insulative tiers and the conductive tiers. The channel-material-string structures individually comprise an upper portion above and joined with a lower portion. Individual of the channel-material-string structures comprise at least one external jog surface in a vertical cross-section where the upper and lower portions join. Other embodiments, including method are disclosed.

TECHNICAL FIELD

Embodiments disclosed herein pertain to memory arrays and to methodsused in forming a memory array.

BACKGROUND

Memory is one type of integrated circuitry and is used in computersystems for storing data. Memory may be fabricated in one or more arraysof individual memory cells. Memory cells may be written to, or readfrom, using digitlines (which may also be referred to as bitlines, datalines, or sense lines) and access lines (which may also be referred toas wordlines). The sense lines may conductively interconnect memorycells along columns of the array, and the access lines may conductivelyinterconnect memory cells along rows of the array. Each memory cell maybe uniquely addressed through the combination of a sense line and anaccess line.

Memory cells may be volatile, semi-volatile, or non-volatile.Non-volatile memory cells can store data for extended periods of time inthe absence of power. Non-volatile memory is conventionally specified tobe memory having a retention time of at least about 10 years. Volatilememory dissipates and is therefore refreshed/rewritten to maintain datastorage. Volatile memory may have a retention time of milliseconds orless. Regardless, memory cells are configured to retain or store memoryin at least two different selectable states. In a binary system, thestates are considered as either a “0” or a “1”. In other systems, atleast some individual memory cells may be configured to store more thantwo levels or states of information.

A field effect transistor is one type of electronic component that maybe used in a memory cell. These transistors comprise a pair ofconductive source/drain regions having a semiconductive channel regionthere-between. A conductive gate is adjacent the channel region andseparated there-from by a thin gate insulator. Application of a suitablevoltage to the gate allows current to flow from one of the source/drainregions to the other through the channel region. When the voltage isremoved from the gate, current is largely prevented from flowing throughthe channel region. Field effect transistors may also include additionalstructure, for example a reversibly programmable charge-storage regionas part of the gate construction between the gate insulator and theconductive gate.

Flash memory is one type of memory and has numerous uses in moderncomputers and devices. For instance, modern personal computers may haveBIOS stored on a flash memory chip. As another example, it is becomingincreasingly common for computers and other devices to utilize flashmemory in solid state drives to replace conventional hard drives. As yetanother example, flash memory is popular in wireless electronic devicesbecause it enables manufacturers to support new communication protocolsas they become standardized, and to provide the ability to remotelyupgrade the devices for enhanced features.

NAND may be a basic architecture of integrated flash memory. A NAND cellunit comprises at least one selecting device coupled in series to aserial combination of memory cells (with the serial combination commonlybeing referred to as a NAND string). NAND architecture may be configuredin a three-dimensional arrangement comprising vertically-stacked memorycells individually comprising a reversibly programmable verticaltransistor. Control or other circuitry may be formed below thevertically-stacked memory cells. Other volatile or non-volatile memoryarray architectures may also comprise vertically-stacked memory cellsthat individually comprise a transistor.

Memory arrays may be arranged in memory pages, memory blocks and partialblocks (e.g., sub-blocks), and memory planes, for example as shown anddescribed in any of U.S. Patent Application Publication Nos.2015/0228651, 2016/0267984, and 2017/0140833. The memory blocks may atleast in part define longitudinal outlines of individual wordlines inindividual wordline tiers of vertically-stacked memory cells.Connections to these wordlines may occur in a so-called “stair-stepstructure” at an end or edge of an array of the vertically-stackedmemory cells. The stair-step structure includes individual “stairs”(alternately termed “steps” or “stair-steps”) that define contactregions of the individual wordlines upon which elevationally-extendingconductive vias contact to provide electrical access to the wordlines.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic cross-sectional view of a portion of asubstrate in process in accordance with an embodiment of the inventionand is taken through line 1-1 in FIG. 2.

FIG. 2 is a diagrammatic cross-sectional view taken through line 2-2 inFIG. 1.

FIGS. 3-10 and 14-38 are diagrammatic sequential sectional, expanded,enlarged, and/or partial views of the construction of FIGS. 1 and 2, orportions thereof, in process in accordance with some embodiments of theinvention.

FIGS. 11-13 and 39-53 are diagrammatic cross-sectional views of portionsof substrates in process in accordance with some embodiments of theinvention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Embodiments of the invention encompass methods used in forming a memoryarray, for example an array of NAND or other memory cells that may haveat least some peripheral control circuitry under the array (e.g.,CMOS-under-array). Embodiments of the invention encompass so-called“gate-last” or “replacement-gate” processing, so-called “gate-first”processing, and other processing whether existing or future-developedindependent of when transistor gates are formed. Embodiments of theinvention also encompass a memory array (e.g., NAND architecture)independent of method of manufacture. First example method embodimentsare described with reference to FIGS. 1-53 which may be considered as a“gate-last” or “replacement-gate” process, and starting with FIGS. 1 and2.

FIGS. 1 and 2 show a construction 10 having an array or array area 12 inwhich elevationally-extending strings of transistors and/or memory cellswill be formed. Construction 10 comprises a base substrate 11 having anyone or more of conductive/conductor/conducting,semiconductive/semiconductor/semiconducting, orinsulative/insulator/insulating (i.e., electrically herein) materials.Various materials have been formed elevationally over base substrate 11.Materials may be aside, elevationally inward, or elevationally outwardof the FIGS. 1 and 2—depicted materials. For example, other partially orwholly fabricated components of integrated circuitry may be providedsomewhere above, about, or within base substrate 11. Control and/orother peripheral circuitry for operating components within an array(e.g., array 12) of elevationally-extending strings of memory cells mayalso be fabricated and may or may not be wholly or partially within anarray or sub-array. Further, multiple sub-arrays may also be fabricatedand operated independently, in tandem, or otherwise relative oneanother. In this document, a “sub-array” may also be considered as anarray.

In some embodiments and as shown, a conductor tier 16 comprisingconductor material 17 (e.g., conductively-doped polysilicon atopWSi_(x)) has been formed above substrate 11. Conductor tier 16 maycomprise part of control circuitry (e.g., peripheral-under-arraycircuitry and/or a common source line or plate) used to control read andwrite access to the transistors and/or memory cells that will be formedwithin array 12.

A lower portion 18L of a stack 18* has been formed above substrate 11and conductor tier 16 when present (an * being used as a suffix to beinclusive of all such same-numerically-designated components that may ormay not have other suffixes). Stack 18* will comprisevertically-alternating conductive tiers 22* and insulative tiers 20*.Example lower portion 18L is shown as comprising two insulative tiers20* and two conductive tiers 22*. More insulative tiers 20*, moreconductive tiers 22*, less insulative tiers 20*, or less conductivetiers 22* may alternately be provided in lower portion 18L (not shown).Conductive tiers 22* (alternately referred to as first tiers) may notcomprise conducting material and insulative tiers 20* (alternatelyreferred to as second tiers) may not comprise insulative material or beinsulative at this point in processing in conjunction with the herebyinitially-described example method embodiment which is “gate-last” or“replacement-gate”. Example conductive tiers 22* comprise first material26 (e.g., silicon nitride) which may be wholly or partially sacrificial.Example insulative tiers 20* comprise second material (e.g., 24, 27;such as one or more insulative oxides including, for example, silicondioxide) that is of different composition from that of first material 26and which may be wholly or partially sacrificial. In one embodiment, alowest first tier 22 z comprises first sacrificial material 77 (e.g.,polysilicon or silicon nitride, and may be of the same or differentcomposition from that of material of first tiers 22* there-above and/orthat will be formed there-above). In one embodiment, a next-lowest firsttier 22 x comprises conductively-doped polysilicon 47.

Example thickness for each of tiers 20* and 22* is 20 to 60 nanometers.In one embodiment and as shown, lowest first tier 22 z is not directlyagainst conductor material 17 of conductor tier 16, for example where alowest second tier 20 z is vertically between conductor material 17 ofconductor tier 16 and lowest first tier 22 z. Alternately, the lowestfirst tier may be directly against the conductor material of theconductor tier (not shown). In one embodiment, lowest second tier 20 zis directly against a top 19 of conductor material 17 of conductor tier16. A silicon nitride layer (not shown) may be between second material24 and first sacrificial material 77, and thereby be a part ofinsulative tier 20 z. A silicon nitride layer (not shown) may be betweensecond material 27 and first-tier material 47, and thereby be a part ofinsulative tier 20 x.

Stack 18* comprises laterally-spaced memory-block regions 58 that willcomprise laterally-spaced memory blocks 58 in a finished circuitryconstruction. In this document, “block” is generic to include“sub-block”. Memory-block regions 58 and resultant memory blocks 58 (notyet shown) may be considered as being longitudinally elongated andoriented, for example along a direction 55. Memory-block regions 58 maynot be discernable at this point of processing.

In one embodiment, horizontally-elongated lines 13 have been formed inin next-lowest first tier 22 x (and in one embodiment in tier 20 x).Lines 13 are individually between immediately-laterally-adjacentmemory-block regions 58. Lines 13 comprise second sacrificial material15 which, in one embodiment, is of different composition from firstsacrificial material 77. In some embodiments, “second sacrificialmaterial” is just referred to as “sacrificial material”. In oneembodiment, second sacrificial material 15 is of different compositionfrom first-tier material that is (e.g., 47) or will be formed abovefirst sacrificial material 77 and from second-tier material that is(e.g., 27) or will be formed above first sacrificial material 77. In oneembodiment, second sacrificial material 15 is of different compositionfrom material 47 of next-lowest conductive first tier 22 x. In oneembodiment, second sacrificial material 15 comprises metal material, forexample elemental tungsten above a thin layer of TiN. In one embodiment,an insulator material 24 (e.g., silicon dioxide) may formed in trenchesformed in materials 47 and 27 as shown before forming material 47 andthereby be laterally between materials 47 and 15 as shown. Regardless,lines 13 may taper laterally-inward (not shown) moving deeper into lowerstack portion 18L. Lines 13 may be considered as having bottom surfaces59. In one embodiment and as shown, individual bottom-line surfaces 59are everywhere above lowest first tier 22 z.

In one embodiment, pillars 60 have been formed in lower portion 18L.Pillars 60 are horizontally-located (i.e., in x, y coordinates) whereindividual channel-material-string structures will be formed. By way ofexample and for brevity only, pillars 60 are shown as being arranged ingroups or columns of staggered rows of four and five pillars 60 per row.In one embodiment, pillars 60 comprise second sacrificial material 15.Pillars 60 may taper radially-inward (not shown) moving deeper intolower stack portion 18L. Pillars 60 may be considered as having bottomsurfaces 64 and uppermost surfaces 63. In embodiments where both ofpillars 60 and lines 13 are formed, such may be formed at the same timeor at different times.

In one embodiment, pillar-bottom surfaces 64 and line-bottom surfaces 59are at different depths relative one another. In one such embodiment,the pillar-bottom surfaces 64 are deeper than line-bottom surfaces 59,and in one such latter embodiment are in conductor tier 16 (e.g.,directly against conductor material 17). In one embodiment,pillar-uppermost surfaces 63 are individually above lowest first tier 22z.

Referring to FIGS. 3 and 4, vertically-alternating first tiers 22 andsecond tiers 20 of an upper portion 18U of stack 18* have been formedabove lower portion 18L (and lines 13 and/or pillars 60 when present).Example upper portion 18U is shown starting above lower portion 18L witha second tier 20 although such could alternately start with a first tier22 (not shown). Regardless, only a small number of tiers 20 and 22 isshown, with more likely upper portion 18U (and thereby stack 18*)comprising dozens, a hundred or more, etc. of tiers 20* and 22*.Further, other circuitry that may or may not be part of peripheraland/or control circuitry may be between conductor tier 16 and stack 18*.By way of example only, multiple vertically-alternating tiers ofconductive material and insulative material of such circuitry may bebelow a lowest of the conductive tiers 22* and/or above an uppermost ofthe conductive tiers 22*. For example, one or more select gate tiers(not shown) may be between conductor tier 16 and the lowest conductivetier 22* and one or more select gate tiers may be above an uppermost ofconductive tiers 22*. Alternately or additionally, at least one of thedepicted uppermost and lowest conductive tiers 22* may be a select gatetier.

Channel openings 25 have been formed (e.g., by etching) throughinsulative tiers 20 and conductive tiers 22 in upper portion 18U tolower portion 18L and individually to pillars 60 when present.Alternately, channel openings 25 may extend to lowest first tier 22 z(including to therein or to there-below) if pillars 60 are not present.Regardless, channel openings 25 may taper radially-inward (as shown)moving deeper into upper stack portion 18U.

Referring to FIGS. 5 and 6, pillars 60 (not shown) have been removed(e.g., by isotropic etching) through channel openings 25 therebyeffectively extending channel openings 25 into individual void-spaces 61resulting from the removing of pillars 60 and to lowest first tier 22 z.The artisan is capable of selecting a suitable isotropic etchingchemistry that will etch pillar material 15 selectively relative toother exposed materials. As an example, a W material 15 can beisotropically etched selectively relative to SiO₂ and Si₃N₄ using amixture of ammonia and hydrogen peroxide or a mixture of sulfuric acidand hydrogen peroxide.

Referring to FIGS. 7-10, transistor channel material 36 has been formedin individual channel openings 25 and void-spaces 61 elevationally alongthe first tiers and the second tiers. Channel material 36 will bedirectly electrically coupled with conductive material 17 in conductortier 16. Individual memory cells of the example memory array beingformed may comprise a gate region (e.g., a control-gate region) and amemory structure laterally between the gate region and the channelmaterial. In one such embodiment, the memory structure is formed tocomprise a charge-blocking region, storage material (e.g.,charge-storage material), and an insulative charge-passage material. Thestorage material (e.g., floating gate material such as doped or undopedsilicon or charge-trapping material such as silicon nitride, metal dots,etc.) of the individual memory cells is elevationally along individualof the charge-blocking regions. The insulative charge-passage material(e.g., a band gap-engineered structure having nitrogen-containingmaterial [e.g., silicon nitride] sandwiched between two insulator oxides[e.g., silicon dioxide]) is laterally between the channel material andthe storage material. FIGS. 10 and 11 show one embodiment whereincharge-blocking material 30, storage material 32, and charge-passagematerial 34 have been formed in individual channel openings 25elevationally along insulative tiers 20* and conductive tiers 22*.Transistor materials 30, 32, and 34 (e.g., memory-cell materials) may beformed by, for example, deposition of respective thin layers thereofover stack 18* and within individual openings 25 followed by planarizingsuch back at least to a top surface of stack 18*. Collectively, channelmaterial 36 along with materials 30, 32, and 34 may be considered ascomprising individual channel-material-string structures 53 that extendthrough first tiers 22* and second tiers 20* in upper portion 18U tolowest first tier 22 z in lower portion 18L.

Channel material 36 may be considered as having a lowest surface 71thereof. Channel-material-string structures 53 in one embodiment havememory-cell materials (e.g., 30, 32, and 34) there-along and withsecond-tier material (e.g., 24) being horizontally-betweenimmediately-adjacent channel-material-string structures 53. Materials30, 32, 34, and 36 are collectively shown as and only designated asmaterial 37 in FIGS. 13 and 14 due to scale. Example channel materials36 include appropriately-doped crystalline semiconductor material, suchas one or more silicon, germanium, and so-called III/V semiconductormaterials (e.g., GaAs, InP, GaP, and GaN). Example thickness for each ofmaterials 30, 32, 34, and 36 is 25 to 100 Angstroms. Punch etching maybe conducted to remove materials 30, 32, and 34 from the bases ofchannel openings 25 (not shown) to expose conductor tier 16 such thatchannel material 36 is directly against conductor material 17 ofconductor tier 16. Such punch etching may occur separately with respectto each of materials 30, 32, and 34 (as shown) or may occur with respectto only some (not shown). Alternately, and by way of example only, nopunch etching may be conducted and channel material 36 may be directlyelectrically coupled to conductor material 17 of conductor tier 16 onlyby a separate conductive interconnect (not yet shown). Channel openings25 are shown as comprising a radially-central solid dielectric material38 (e.g., spin-on-dielectric, silicon dioxide, and/or silicon nitride).Alternately, and by way of example only, the radially-central portionwithin channel openings 25 may include void space(s) (not shown) and/orbe devoid of solid material (not shown).

In one embodiment, channel-material-string structures 53 may beconsidered as individually comprising an upper portion 70 above andjoined with a lower portion 72. Individual channel-material-stringstructures 53 comprise at least one external jog surface 75 (FIG. 10) ina vertical cross-section (e.g., that of FIGS. 8 and 10) where upperportion 70 and lower portions 72 join (i.e., a “jog surface” hereinbeing characterized by an abrupt change in direction [at least 15° ] incomparison to external surfaces of a channel-material-string structurethat are immediately-above and immediately-below the jog surface). Oneor more jog surfaces 75 may form due to radially inward taper of channelopenings 25 moving deeper into upper stack portion 18U in comparison toa larger uppermost radial extent of void-spaces 61 left by removal ofpillars 60 (as shown). Alternately and/or additionally, one or more jogsurfaces 75 may result from misalignment (not shown in FIGS. 7-10) ofchannel openings 25 relative to former pillars 60, for example as isdescribed below.

In one embodiment, the at least one external jog surface 75 ishorizontal (as shown) or within 10° of horizontal. Example individualchannel-material-string structures 53 comprise two jog surfaces 75, andwhich in one embodiment are angled from vertical the same relative oneanother (e.g., each being horizontal in the one example and thereby eachbeing angled 90° from vertical).

FIG. 11 shows an example alternate embodiment construction 10 a. Likenumerals from the above-described embodiments have been used whereappropriate, with some construction differences being indicated with thesuffix “a” or with different numerals. Individualchannel-material-string structures 53 a comprise only one jog surface 75a, for example that might occur due to slight misalignment of channelopenings 25 relative to former pillars 60. Any other attribute(s) oraspect(s) as shown and/or described herein with respect to otherembodiments may be used.

FIG. 12 shows an example alternate embodiment construction 10 b. Likenumerals from the above-described embodiments have been used whereappropriate, with some construction differences being indicated with thesuffix “b” or with different numerals. Individualchannel-material-string structures 53 b comprise at least one jogsurface 75 b that is not horizontal (e.g., two jog surfaces 75 b beingshown, one of which is horizontal and one of which is not horizontal).In one embodiment, jog surface 75 b that is not horizontal is more than100 from horizontal, in one such embodiment is at least 22.5° fromhorizontal, and in one such is embodiment is at least 45° fromhorizontal (about 66° from horizontal being shown, and thereby about 24°from each of example exterma; vertical surfaces ofchannel-material-string structure 53 above and below jog surfaces 75 b).Any other attribute(s) or aspect(s) as shown and/or described hereinwith respect to other embodiments may be used.

FIG. 13 shows an example alternate embodiment construction 10 c whereinindividual channel-material-string structures 53 c comprise a jogsurface 75 c that is 45° from horizontal (the left one). Like numeralsfrom the above-described embodiments have been used where appropriate,with some construction differences being indicated with the suffix “b”or with different numerals. Any other attribute(s) or aspect(s) as shownand/or described herein with respect to other embodiments may be used.

Referring to FIGS. 14 and 15, horizontally-elongated trenches 40 havebeen formed into stack 18* (e.g., by anisotropic etching) and areindividually between immediately-laterally-adjacent memory-block regions58 and extend to line 13 there-between.

Referring to FIGS. 16 and 17, second sacrificial material 15 (not shown)of lines 13 (not shown) has been removed through trenches 40 (e.g., byisotropic etching using a mixture of ammonia and hydrogen peroxide or amixture of sulfuric acid and hydrogen peroxide if material 15 comprisesW). Intervening material (not yet shown) is ultimately formed intrenches 40 and void-spaces left as a result of the removing of secondsacrificial material 15 of lines 13.

Any other attribute(s) or aspect(s) as shown and/or described hereinwith respect to other embodiments may be used in the embodiments shownand described with reference to the above embodiments. In someembodiments, other and/or additional processing occurs, for example asdescribed below.

Referring to FIGS. 18 and 19, trenches 40 have been optionally linedwith lining material 35 (e.g., 35 being hafnium oxide, aluminum oxide,silicon dioxide, silicon nitride, etc.). Lining material 35 may bepartly or wholly sacrificial and ideally is of a composition other thanthat of materials 24 and 26. After deposition of lining material 35, ithas been substantially removed from being over horizontal surfaces, forexample by maskless anisotropic spacer-like etching thereof.

Referring to FIGS. 20 and 21, trenches 40 have been extended toconductor material 17 of conductor tier 16 (e.g., by etching throughmaterials 27, 77, and 24).

Referring to FIGS. 22-24, first sacrificial material 77 (not shown) hasbeen isotropically etched from lowest first tier 22 z through trenches40 (e.g., using liquid or vapor H₃PO₄ as a primary etchant wherematerial 77 is silicon nitride and exposed other materials comprise oneor more oxides or polysilicon or using tetramethyl ammonium hydroxide[TMAH] where material 77 is polysilicon). If first-tier material 26 andfirst sacrificial material 77 are of the same composition, sidewalls offirst-tier material 26 have been masked by lining material 35 whichprecludes material 26 from being etched while etching first sacrificialmaterial 77.

In one embodiment, a sidewall of the channel material of thechannel-material-string structures in the lowest first tier is exposed.FIGS. 25 and 26 show example such subsequent processing wherein, in oneembodiment, material 30 (e.g., silicon dioxide), material 32 (e.g.,silicon nitride), and material 34 (e.g., silicon dioxide or acombination of silicon dioxide and silicon nitride) have been etched intier 20 z to expose a sidewall 41 of channel material 36 ofchannel-material-string structures 53 in lowest first tier 22 z. Any ofmaterials 30, 32, and 34 in tier 22 z may be considered as beingsacrificial material therein. As an example, consider an embodimentwhere materials 35 is one or more insulative oxides (other than silicondioxide), materials 47 and 36 are polysilicon, and memory-cell materials30, 32, and 34 individually are one or more of silicon dioxide andsilicon nitride layers. In such example, the depicted construction canresult by using modified or different chemistries for sequentiallyetching silicon dioxide and silicon nitride selectively relative to theother. As examples, a solution of 100:1 (by volume) water to HF willetch silicon dioxide selectively relative to silicon nitride, whereas asolution of 1000:1 (by volume) water to HF will etch silicon nitrideselectively relative to silicon dioxide. Accordingly, and in suchexample, such etching chemistries can be used in an alternating mannerwhere it is desired to achieve the example construction shown by FIGS.25 and 26. The artisan is capable of selecting other chemistries foretching other different materials where a construction as shown in FIGS.25 and 26 is desired.

Referring to FIGS. 27 and 28, and in one embodiment, conductive material42 has been deposited into void-space in lowest first tier 22 z left asa result of removing first sacrificial material 77. In one suchembodiment, conductive material 42 is directly against exposed sidewall41 of the channel material 36 of channel-material-string structures 53in lowest first tier 22 z and in one embodiment is directly against anuppermost surface 19 of conductor material 17 of conductor tier 16. Suchis but one example whereby conductive material 42 has been deposited todirectly electrically couple together channel material 36 of individualchannel-material-string structures 53 and conductor material 17 ofconductor tier 16 (e.g., through channel-material sidewall 41). Exampleconductive materials 42 are conductively-doped semiconductor material(e.g., conductively-doped polysilicon) and metal material. Conductivematerial 42 may be directly against first-tier material 47. Conductivematerial 42 may not be directly against first-tier material 47 (notshown), for example if a silicon nitride layer (not shown and referredto above) was between second material 27 (not shown) and first-tiermaterial 47. First-tier material 47 may or may not be in the finishedconstruction, and if so may or may not be circuit inoperative.

Referring to FIGS. 29 and 30, conductive material 42 has been removedfrom trenches 40, for example by timed isotropic or anisotropic etchingthat may be conducted selectively relative to materials 24, 26, 17, and47. Such may result in removal of lining material 35 as shown or suchmay be separately removed. Alternately, lining material 35 may have beenremoved earlier (not shown). A reason for removing lining material 35 isto provide access to material 26 in second tiers 22 for removal thereofin a replacement-gate process. The etching of conductive material 42 mayresult in some etching of conductor material 17 when exposed (notshown). Example etching chemistries where material 42 isconductively-doped polysilicon, material 24 is silicon dioxide, material26 is silicon dioxide is HBr (anisotropic) and TMAH (isotropic).

Referring to FIGS. 31 and 32, an optional selective oxidation has beenconducted, thus forming an oxide layer 45 (e.g., silicon dioxide).

Referring to FIGS. 33-38, material 26 (not shown) of conductive tiers22* has been removed, for example by being isotropically etched awaythrough trenches 40 ideally selectively relative to the other exposedmaterials (e.g., using liquid or vapor H₃PO₄ as a primary etchant wherematerial 26 is silicon nitride and other materials comprise one or moreoxides or polysilicon). Material 26 (not shown) in conductive tiers 22*in the example embodiment is sacrificial and has been replaced withconducting material 48, and which has thereafter been removed fromtrenches 40, thus forming individual conductive lines 29 (e.g.,wordlines) and elevationally-extending strings 49 of individualtransistors and/or memory cells 56.

A thin insulative liner (e.g., Al₂O₃ and not shown) may be formed beforeforming conducting material 48. Approximate locations of transistorsand/or memory cells 56 are indicated with a bracket in FIG. 38 and somewith dashed outlines in FIGS. 33, 35, and 37, with transistors and/ormemory cells 56 being essentially ring-like or annular in the depictedexample. Alternately, transistors and/or memory cells 56 may not becompletely encircling relative to individual channel openings 25 suchthat each channel opening 25 may have two or moreelevationally-extending strings 49 (e.g., multiple transistors and/ormemory cells about individual channel openings in individual conductivetiers with perhaps multiple wordlines per channel opening in individualconductive tiers, and not shown). Conducting material 48 may beconsidered as having terminal ends 50 (FIG. 38) corresponding tocontrol-gate regions 52 of individual transistors and/or memory cells56. Control-gate regions 52 in the depicted embodiment compriseindividual portions of individual conductive lines 29. Materials 30, 32,and 34 may be considered as a memory structure 65 that is laterallybetween control-gate region 52 and channel material 36. In oneembodiment and as shown with respect to the example “gate-last”processing, conducting material 48 of conductive tiers 22* is formedafter forming channel openings 25 and/or trenches 40. Alternately, theconducting material of the conductive tiers may be formed before formingchannel openings 25 and/or trenches 40 (not shown), for example withrespect to “gate-first” processing.

A charge-blocking region (e.g., charge-blocking material 30) is betweenstorage material 32 and individual control-gate regions 52. A chargeblock may have the following functions in a memory cell: In a programmode, the charge block may prevent charge carriers from passing out ofthe storage material (e.g., floating-gate material, charge-trappingmaterial, etc.) toward the control gate, and in an erase mode the chargeblock may prevent charge carriers from flowing into the storage materialfrom the control gate. Accordingly, a charge block may function to blockcharge migration between the control-gate region and the storagematerial of individual memory cells. An example charge-blocking regionas shown comprises insulator material 30. By way of further examples, acharge-blocking region may comprise a laterally (e.g., radially) outerportion of the storage material (e.g., material 32) where such storagematerial is insulative (e.g., in the absence of anydifferent-composition material between an insulative storage material 32and conducting material 48). Regardless, as an additional example, aninterface of a storage material and conductive material of a controlgate may be sufficient to function as a charge-blocking region in theabsence of any separate-composition-insulator material 30. Further, aninterface of conducting material 48 with material 30 (when present) incombination with insulator material 30 may together function as acharge-blocking region, and as alternately or additionally may alaterally-outer region of an insulative storage material (e.g., asilicon nitride material 32). An example material 30 is one or more ofsilicon hafnium oxide and silicon dioxide.

In one embodiment and as shown, lowest surface 71 of channel material 36of channel-material-string structures 53 is never directly against anyof conductor material 17 of conductor tier 16.

Intervening material 57 has been formed in trenches 40 and void-spacesleft as a result of the removing of second sacrificial material 15 oflines 13, and thereby laterally-between and longitudinally-alongimmediately-laterally-adjacent memory blocks 58. Intervening material 57may provide lateral electrical isolation (insulation) betweenimmediately-laterally-adjacent memory blocks. Such may include one ormore of insulative, semiconductive, and conducting materials and,regardless, may facilitate conductive tiers 22 from shorting relativeone another in a finished circuitry construction. Example insulativematerials are one or more of SiO₂, Si₃N₄, Al₂O₃, and undopedpolysilicon. Intervening material 57 may include through array vias (notshown). Some material in trenches 40 formed prior to forming that whichis designated as intervening material 57 may remain and thereby comprisepart of the intervening material 57. Regardless, in one embodiment atleast a majority of intervening material 57 is formed in the trenchesand void spaces after forming conductive material 42.

Any other attribute(s) or aspect(s) as shown and/or described hereinwith respect to other embodiments may be used in the embodiments shownand described with reference to the above embodiments.

FIGS. 39, 40, and 41 show example resultant constructions 10 a, 10 b,and 10 c, respectively, that may result from FIGS. 11, 12, and 13,respectively. Any other attribute(s) or aspect(s) as shown and/ordescribed herein with respect to other embodiments may be used.

FIGS. 42 and 43 show an example alternate embodiment construction 10 din process in accordance with an embodiment of the invention. Likenumerals from the above-described embodiments have been used whereappropriate, with some construction differences being indicated with thesuffix “d” or with different numerals. FIG. 42 corresponds in processingsequence to that of FIG. 2. Construction 10 d has individual lines 13 dthat have a bottom surface 59 that is below a top 73 of lowest firsttier 22 z. Further, in one such embodiment and as shown, lines 13 dindividually comprise laterally-opposing projections 54longitudinally-there-along that are in lowest first tier 22 z. Analogousand/or alternate processing to that shown and described above may occurto result in a construction 10 d as shown in FIG. 43 (which correspondsin sequence and view to that of FIG. 35 of the first-describedembodiment). Any other attribute(s) or aspect(s) as shown and/ordescribed herein with respect to other embodiments may be used.

An alternate method is described with reference to FIGS. 44-48. Likenumerals from the above-described embodiments have been used whereappropriate, with some construction differences being indicated with thesuffix “e” or with different numerals. FIG. 44 corresponds in processingsequence to that of FIG. 2. Example construction 10 e has conductormaterial 17 of conductor tier 16 as comprising upper conductor material43 (e.g., n-type or p-type conductively-doped polysilicon) directlyabove (e.g., directly against) lower conductor material 44 (e.g.,WSi_(x)) of different composition from upper conductor material 43.Second tier 20 x that is immediately-above lowest first tier 22 zcomprises undoped polysilicon 51 (as well as second tiermaterials/layers 27 and 24). A silicon nitride layer (not shown) may bebetween second material 27 and undoped polysilicon 51, and thereby be apart of insulative tier 20 x. Horizontally-elongated troughs 79 havebeen formed in lower portion 18L and extend to conductor tier 16.

Referring to FIGS. 45 and 46, exposed portions of conductor material 43of conductor tier 16 and undoped polysilicon 51 have been oxidized, thusforming insulative oxide 45 (e.g., silicon dioxide; e.g.,longitudinally-along what will be lines 13 e).

Thereafter, and referring to FIG. 47, horizontally-elongated lines 13 ehave been formed in troughs 79 and are individually betweenimmediately-laterally-adjacent memory-block regions 58. Example lines 13e comprise second sacrificial material 15. In one embodiment, bottomsurface 59 of individual lines 13 e is in conductor tier 16 and in onesuch embodiment is not directly against the conductor material thereof(e.g., due to presence of insulating oxide 45).

Analogous and/or alternate processing to that shown and described abovemay occur to result in a construction 10 e as shown in FIG. 48 (whichcorresponds in sequence and view to that of FIG. 35 of thefirst-described embodiment). Any other attribute(s) or aspect(s) asshown and/or described herein with respect to other embodiments may beused.

An alternate method to that of shown and described with reference toFIGS. 44-48 is described with reference to FIGS. 49-53. Like numeralsfrom the above-described embodiments have been used where appropriate,with some construction differences being indicated with the suffix “f”or with different numerals. FIGS. 49 and 50 corresponds in processingsequence to that of FIGS. 44 and 46, collectively. Undoped polysilicon51 has been laterally recessed (e.g., by isotropic etching) to formlaterally-opposed recesses 78 longitudinally-along individual troughs79. In one embodiment, laterally-opposed recesses 78 have also beenformed in conductor material 17 as shown.

Referring to FIGS. 51 and 52, horizontally-elongated lines 13 f(comprising second sacrificial material 15) have been formed in troughs79 and are individually between immediately-laterally-adjacentmemory-block regions 58. Lines 13 f individually compriselaterally-opposing projections 66 longitudinally-there-along that are inlaterally-opposed recesses 78. In one embodiment, lines 13 f comprisebottom surfaces 59 that are in conductor tier 16. In one embodimentwhere laterally-opposed recesses 78 have also been formed in conductormaterial 43, lines 13 f also individually comprise laterally-opposingprojections 54 longitudinally-there-along that are in laterally-opposedrecesses 78 in conductor material 43.

Analogous and/or alternate processing to that shown and described abovemay occur to result in a construction 10 f as shown in FIG. 53 (whichcorresponds in sequence and view to that of FIG. 35 of thefirst-described embodiment). Any other attribute(s) or aspect(s) asshown and/or described herein with respect to other embodiments may beused.

In some embodiments, a method used in forming a memory array (e.g., 12)comprising strings (e.g., 49) of memory cells (e.g., 56) comprisesforming a lower portion (e.g., 18L) of a stack (e.g., 18*) that willcomprise vertically-alternating first tiers (e.g., 22*) and second tiers(e.g., 20*). The stack comprises laterally-spaced memory-block regions(e.g., 58). Material of the first tiers is of different composition frommaterial of the second tiers. Pillars (e.g., 60) are formed in the lowerportion and are individually horizontally-located where individualchannel-material-string structures (e.g., 53) will be formed. Thepillars comprising sacrificial material (e.g., 15).Vertically-alternating first tiers and second tiers of an upper portion(e.g., 18U) of the stack is formed above the lower portion and thepillars. Channel openings (e.g., 25) are formed into the stack andindividually extend to individual of the pillars. The sacrificialmaterial of the pillars is removed through the channel openings toextend the channel openings deeper into the stack.Channel-material-string structures are formed in the extended channelopenings and in void-space therein resulting from the removing of thepillars. Any other attribute(s) or aspect(s) as shown and/or describedherein with respect to other embodiments may be used.

In some embodiments, a method used in forming a memory array (e.g., 12)comprising strings (e.g., 49) of memory cells (e.g., 56) comprisesforming a conductor tier (e.g., 16) comprising conductor material (e.g.,17) on a substrate (e.g., 11). A lower portion (e.g., 18L) of a stack(e.g., 18*) that will comprise vertically-alternating first tiers (e.g.,22*) and second tiers (e.g., 20*) is formed above the conductor tier.The stack comprising laterally-spaced memory-block regions (e.g., 58).Material of the first tiers is of different composition from material ofthe second tiers. A lowest of the first tiers (e.g., 22 z) comprisesfirst sacrificial material (e.g., 77). Pillars (e.g., 60) are formed inthe lowest first tier and are individually horizontally-located whereindividual channel-material-string structures (e.g., 53) will be formed.The pillars comprise second sacrificial material (e.g., 15).Vertically-alternating first tiers and second tiers of an upper portion(e.g., 18U of the stack ae formed above the lower portion and thepillars. Channel openings (e.g., 25) are formed into the stack andindividually extend to individual of the pillars. The second sacrificialmaterial of the pillars is removed through the channel openings toextend the channel openings deeper into the stack.Channel-material-string structures are formed in the extended channelopenings and in void-space therein resulting from the removing of thepillars. Horizontally-elongated trenches (e.g., 40) are formed into thestack and are individually between immediately-laterally-adjacent of thememory-block regions and extend to the first sacrificial material in thelowest first tier. The first sacrificial material is isotropicallyetched from the lowest first tier through the trenches. After theisotropically etching, conductive material (e.g., 42) is formed in thelowest first tier that directly electrically couples together thechannel material of the individual channel-material-string structuresand the conductor material of the conductor tier. Any other attribute(s)or aspect(s) as shown and/or described herein with respect to otherembodiments may be used.

Alternate embodiment constructions may result from method embodimentsdescribed above, or otherwise. Regardless, embodiments of the inventionencompass memory arrays independent of method of manufacture.Nevertheless, such memory arrays may have any of the attributes asdescribed herein in method embodiments. Likewise, the above-describedmethod embodiments may incorporate, form, and/or have any of theattributes described with respect to device embodiments.

In one embodiment, a memory array (e.g., 12) comprising strings (e.g.,49) of memory cells (e.g., 56) comprises a conductor tier (e.g., 16)comprising conductor material (e.g., 17). The memory array compriseslaterally-spaced memory blocks (e.g., 58) individually comprising avertical stack (e.g., 18*) comprising alternating insulative tiers(e.g., 20*) and conductive tiers (e.g., 22*). Channel-material-stringstructures (e.g., 53) of memory cells extend through the insulativetiers and the conductive tiers. The channel-material-string structuresindividually comprise an upper portion (e.g., 70) above and joined witha lower portion (e.g., 72). Individual of the channel-material-stringstructures comprising at least one external jog surface (e.g., 75, 75 a,75 b, 75 c) in a vertical cross-section where the upper and lowerportions join. Any other attribute(s) or aspect(s) as shown and/ordescribed herein with respect to other embodiments may be used.

The above processing(s) or construction(s) may be considered as beingrelative to an array of components formed as or within a single stack orsingle deck of such components above or as part of an underlying basesubstrate (albeit, the single stack/deck may have multiple tiers).Control and/or other peripheral circuitry for operating or accessingsuch components within an array may also be formed anywhere as part ofthe finished construction, and in some embodiments may be under thearray (e.g., CMOS under-array). Regardless, one or more additional suchstack(s)/deck(s) may be provided or fabricated above and/or below thatshown in the figures or described above. Further, the array(s) ofcomponents may be the same or different relative one another indifferent stacks/decks and different stacks/decks may be of the samethickness or of different thicknesses relative one another. Interveningstructure may be provided between immediately-vertically-adjacentstacks/decks (e.g., additional circuitry and/or dielectric layers).Also, different stacks/decks may be electrically coupled relative oneanother. The multiple stacks/decks may be fabricated separately andsequentially (e.g., one atop another), or two or more stacks/decks maybe fabricated at essentially the same time.

The assemblies and structures discussed above may be used in integratedcircuits/circuitry and may be incorporated into electronic systems. Suchelectronic systems may be used in, for example, memory modules, devicedrivers, power modules, communication modems, processor modules, andapplication-specific modules, and may include multilayer, multichipmodules. The electronic systems may be any of a broad range of systems,such as, for example, cameras, wireless devices, displays, chip sets,set top boxes, games, lighting, vehicles, clocks, televisions, cellphones, personal computers, automobiles, industrial control systems,aircraft, etc.

In this document unless otherwise indicated, “elevational”, “higher”,“upper”, “lower”, “top”, “atop”, “bottom”, “above”, “below”, “under”,“beneath”, “up”, and “down” are generally with reference to the verticaldirection. “Horizontal” refers to a general direction (i.e., within 10degrees) along a primary substrate surface and may be relative to whichthe substrate is processed during fabrication, and vertical is adirection generally orthogonal thereto. Reference to “exactlyhorizontal” is the direction along the primary substrate surface (i.e.,no degrees there-from) and may be relative to which the substrate isprocessed during fabrication. Further, “vertical” and “horizontal” asused herein are generally perpendicular directions relative one anotherand independent of orientation of the substrate in three-dimensionalspace. Additionally, “elevationally-extending” and “extend(ing)elevationally” refer to a direction that is angled away by at least 45°from exactly horizontal. Further, “extend(ing) elevationally”,“elevationally-extending”, “extend(ing) horizontally”,“horizontally-extending” and the like with respect to a field effecttransistor are with reference to orientation of the transistor's channellength along which current flows in operation between the source/drainregions. For bipolar junction transistors, “extend(ing) elevationally”“elevationally-extending”, “extend(ing) horizontally”,“horizontally-extending” and the like, are with reference to orientationof the base length along which current flows in operation between theemitter and collector. In some embodiments, any component, feature,and/or region that extends elevationally extends vertically or within100 of vertical.

Further, “directly above”, “directly below”, and “directly under”require at least some lateral overlap (i.e., horizontally) of two statedregions/materials/components relative one another. Also, use of “above”not preceded by “directly” only requires that some portion of the statedregion/material/component that is above the other be elevationallyoutward of the other (i.e., independent of whether there is any lateraloverlap of the two stated regions/materials/components). Analogously,use of “below” and “under” not preceded by “directly” only requires thatsome portion of the stated region/material/component that is below/underthe other be elevationally inward of the other (i.e., independent ofwhether there is any lateral overlap of the two statedregions/materials/components).

Any of the materials, regions, and structures described herein may behomogenous or non-homogenous, and regardless may be continuous ordiscontinuous over any material which such overlie. Where one or moreexample composition(s) is/are provided for any material, that materialmay comprise, consist essentially of, or consist of such one or morecomposition(s). Further, unless otherwise stated, each material may beformed using any suitable existing or future-developed technique, withatomic layer deposition, chemical vapor deposition, physical vapordeposition, epitaxial growth, diffusion doping, and ion implanting beingexamples.

Additionally, “thickness” by itself (no preceding directional adjective)is defined as the mean straight-line distance through a given materialor region perpendicularly from a closest surface of animmediately-adjacent material of different composition or of animmediately-adjacent region. Additionally, the various materials orregions described herein may be of substantially constant thickness orof variable thicknesses. If of variable thickness, thickness refers toaverage thickness unless otherwise indicated, and such material orregion will have some minimum thickness and some maximum thickness dueto the thickness being variable. As used herein, “different composition”only requires those portions of two stated materials or regions that maybe directly against one another to be chemically and/or physicallydifferent, for example if such materials or regions are not homogenous.If the two stated materials or regions are not directly against oneanother, “different composition” only requires that those portions ofthe two stated materials or regions that are closest to one another bechemically and/or physically different if such materials or regions arenot homogenous. In this document, a material, region, or structure is“directly against” another when there is at least some physical touchingcontact of the stated materials, regions, or structures relative oneanother. In contrast, “over”, “on”, “adjacent”, “along”, and “against”not preceded by “directly” encompass “directly against” as well asconstruction where intervening material(s), region(s), or structure(s)result(s) in no physical touching contact of the stated materials,regions, or structures relative one another.

Herein, regions-materials-components are “electrically coupled” relativeone another if in normal operation electric current is capable ofcontinuously flowing from one to the other and does so predominately bymovement of subatomic positive and/or negative charges when such aresufficiently generated. Another electronic component may be between andelectrically coupled to the regions-materials-components. In contrast,when regions-materials-components are referred to as being “directlyelectrically coupled”, no intervening electronic component (e.g., nodiode, transistor, resistor, transducer, switch, fuse, etc.) is betweenthe directly electrically coupled regions-materials-components.

Any use of “row” and “column” in this document is for convenience indistinguishing one series or orientation of features from another seriesor orientation of features and along which components have been or maybe formed. “Row” and “column” are used synonymously with respect to anyseries of regions, components, and/or features independent of function.Regardless, the rows may be straight and/or curved and/or paralleland/or not parallel relative one another, as may be the columns.Further, the rows and columns may intersect relative one another at 90°or at one or more other angles (i.e., other than the straight angle).

The composition of any of the conductive/conductor/conducting materialsherein may be metal material and/or conductively-dopedsemiconductive/semiconductor/semiconducting material. “Metal material”is any one or combination of an elemental metal, any mixture or alloy oftwo or more elemental metals, and any one or more conductive metalcompound(s).

Herein, any use of “selective” as to etch, etching, removing, removal,depositing, forming, and/or formation is such an act of one statedmaterial relative to another stated material(s) so acted upon at a rateof at least 2:1 by volume. Further, any use of selectively depositing,selectively growing, or selectively forming is depositing, growing, orforming one material relative to another stated material or materials ata rate of at least 2:1 by volume for at least the first 75 Angstroms ofdepositing, growing, or forming.

Unless otherwise indicated, use of “or” herein encompasses either andboth.

CONCLUSION

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a lower portion of a stackthat will comprise vertically-alternating first tiers and second tierson a substrate. The stack comprises laterally-spaced memory-blockregions. Material of the first tiers is of different composition frommaterial of the second tiers. Pillars are formed in the lower portionthat are individually horizontally-located where individualchannel-material-string structures will be formed. The pillars comprisesacrificial material. The vertically-alternating first tiers and secondtiers of an upper portion of the stack are formed above the lowerportion and the pillars. Channel openings are formed into the stack thatindividually extend to individual of the pillars. The sacrificialmaterial of the pillars is removed through the channel openings toextend the channel openings deeper into the stack.Channel-material-string structures are formed in the extended channelopenings and in void-space therein resulting from said removing.

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a conductor tier comprisingconductor material on a substrate. A lower portion of a stack is formedthat will comprise vertically-alternating first tiers and second tiersabove the conductor tier. The stack comprises laterally-spacedmemory-block regions. Material of the first tiers is of differentcomposition from material of the second tiers. A lowest of the firsttiers comprises first sacrificial material. Pillars are formed in thelowest first tier that are individually horizontally-located whereindividual channel-material-string structures will be formed. Thepillars comprise second sacrificial material. The vertically-alternatingfirst tiers and second tiers of an upper portion of the stack are formedabove the lower portion and the pillars. Channel openings are formedinto the stack that individually extend to individual of the pillars.The second sacrificial material of the pillars is removed through thechannel openings to extend the channel openings deeper into the stack.Channel-material-string structures are formed in the extended channelopenings and in void-space therein resulting from said removing.Horizontally-elongated trenches are formed into the stack that areindividually between immediately-laterally-adjacent of the memory-blockregions and extend to the first sacrificial material in the lowest firsttier. The first sacrificial material is isotropically etched from thelowest first tier through the trenches. After the isotropic etching,conductive material is formed in the lowest first tier that directlyelectrically couples together the channel material of the individualchannel-material-string structures and the conductor material of theconductor tier.

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a conductor tier comprisingconductor material on a substrate. A lower portion of a stack is formedthat will comprise vertically-alternating first tiers and second tiersabove the conductor tier. The stack comprises laterally-spacedmemory-block regions. Material of the first tiers is of differentcomposition from material of the second tiers. A lowest of the firsttiers comprises first sacrificial material. A next-lowest of the firsttiers comprises conductively-doped polysilicon. Horizontally-elongatedlines are formed in the next-lowest first tier that are individuallybetween immediately-laterally-adjacent of the memory-block regions. Thelines comprise second sacrificial material of different composition fromthe first-tier material that is or will be formed above the firstsacrificial material, from the second-tier material that is or will beformed above the first sacrificial material, and from material of thenext-lowest first tier. The vertically-alternating first tiers andsecond tiers of an upper portion of the stack are formed above the lowerportion and the lines. Channel-material-string structures are formedthat extend through the first tiers and the second tiers in the upperportion to the lowest first tier in the lower portion.Horizontally-elongated trenches are formed into the stack that areindividually between the immediately-laterally-adjacent memory-blockregions and extend to the line there-between. The second sacrificialmaterial of the lines is removed through the trenches. Interveningmaterial is formed in the trenches and void-spaces left as a result ofthe removing of the second sacrificial material of the lines.

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a conductor tier comprisingconductor material on a substrate. A lower portion of a stack is formedthat will comprise vertically-alternating first tiers and second tiersabove the conductor tier. The stack comprises laterally-spacedmemory-block regions. Material of the first tiers is of differentcomposition from material of the second tiers. A lowest of the firsttiers comprises first sacrificial material. The second-tier material ofthe second tier that is immediately-above the lowest first tiercomprises undoped polysilicon. Horizontally-elongated troughs are formedin the lowest portion that extend to the conductor tier. Exposedportions of the conductor material of the conductor tier and of theundoped polysilicon are oxidized. After the oxidizing,horizontally-elongated lines are formed in the troughs that areindividually between immediately-laterally-adjacent of the memory-blockregions. The lines comprise second sacrificial material. Thevertically-alternating first tiers and second tiers of an upper portionof the stack are formed above the lower portion and the lines.Channel-material-string structures are formed that extend through firsttiers and the second tiers in the upper portion to the lowest first tierin the lower portion. Horizontally-elongated trenches are formed intothe stack that are individually between theimmediately-laterally-adjacent memory-block regions and extend to theline there-between. The second sacrificial material of the lines isremoved through the trenches. Intervening material is formed in thetrenches and void-spaces left as a result of the removing of the secondsacrificial material of the lines.

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a conductor tier comprisingconductor material on a substrate. A lower portion of a stack is formedthat will comprise vertically-alternating first tiers and second tiersabove the conductor tier. The stack comprises laterally-spacedmemory-block regions. Material of the first tiers is of differentcomposition from material of the second tiers. A lowest of the firsttiers comprises first sacrificial material. The second-tier material ofthe second tier that is immediately-above the lowest first tiercomprises undoped polysilicon. Horizontally-elongated troughs are formedin the lowest portion that extend to the conductor tier. The undopedpolysilicon is laterally recessed to form laterally-opposed recesseslongitudinally-along individual of the troughs. After the recessing,horizontally-elongated lines are formed in the troughs that areindividually between immediately-laterally-adjacent of the memory-blockregions. The lines individually comprise laterally-opposing projectionslongitudinally-there-along that are in the laterally-opposed recesses.The lines comprise second sacrificial material. Thevertically-alternating first tiers and second tiers of an upper portionof the stack are formed above the lower portion and the lines.Channel-material-string structures are formed that extend through firsttiers and the second tiers in the upper portion to the lowest first tierin the lower portion. Horizontally-elongated trenches are formed intothe stack that are individually between theimmediately-laterally-adjacent memory-block regions and extend to theline there-between. The second sacrificial material of the lines isremoved through the trenches. Intervening material is formed in thetrenches and void-spaces left as a result of the removing of the secondsacrificial material of the lines.

In some embodiments, a memory array comprising strings of memory cellscomprises laterally-spaced memory blocks individually comprising avertical stack comprising alternating insulative tiers and conductivetiers. Channel-material-string structures of memory cells extend throughthe insulative tiers and the conductive tiers. Thechannel-material-string structures individually comprise an upperportion above and joined with a lower portion. Individual of thechannel-material-string structures comprises at least one external jogsurface in a vertical cross-section where the upper and lower portionsjoin.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method used in forming a memory array comprising strings of memorycells, comprising: forming a conductor tier comprising conductormaterial on a substrate; forming a lower portion of a stack that willcomprise vertically-alternating first tiers and second tiers above theconductor tier, the stack comprising laterally-spaced memory-blockregions, material of the first tiers being of different composition frommaterial of the second tiers, a lowest of the first tiers comprisingfirst sacrificial material, a next-lowest of the first tiers comprisingconductively-doped polysilicon; forming horizontally-elongated lines inthe next-lowest first tier that are individually betweenimmediately-laterally-adjacent of the memory-block regions; the linescomprising second sacrificial material of different composition from thefirst-tier material that is or will be formed above the firstsacrificial material, from the second-tier material that is or will beformed above the first sacrificial material, and from material of thenext-lowest first tier; forming the vertically-alternating first tiersand second tiers of an upper portion of the stack above the lowerportion and the lines, and forming channel-material-string structuresthat extend through first tiers and the second tiers in the upperportion to the lowest first tier in the lower portion; forminghorizontally-elongated trenches into the stack that are individuallybetween the immediately-laterally-adjacent memory-block regions andextend to the line there-between; removing the second sacrificialmaterial of the lines through the trenches; and forming interveningmaterial in the trenches and void-spaces left as a result of theremoving of the second sacrificial material of the lines.
 2. The methodof claim 1 comprising: exposing the first sacrificial material in thelowest first tier in the trenches; isotropically etching the exposedfirst sacrificial material from the lowest first tier through thetrenches; after the isotropically etching, forming conductive materialin the lowest first tier that directly electrically couples together thechannel material of individual of the channel-material-string structuresand the conductor material of the conductor tier; and after forming theconductive material, forming at least a majority of the interveningmaterial in the trenches and the void-spaces.
 3. The method of claim 1wherein an insulator material is laterally between theconductively-doped polysilicon and the second sacrificial material ofindividual of the lines.
 4. The method of claim 1 wherein individual ofthe lines have a bottom surface that is everywhere above the lowestfirst tier.
 5. The method of claim 1 wherein individual of the lineshave a bottom surface that is below a top of the lowest first tier. 6.The method of claim 5 wherein the lines individually compriselaterally-opposing projections longitudinally-there-along that are inthe lowest tier.
 7. The method of claim 1 comprising: forming pillars inthe lower portion prior to forming the upper portion, the pillarsindividually being horizontally-located where individual of thechannel-material-string structures will be formed; removing the pillarsprior to forming the channel-material-string structures; and forming thechannel-material-string structures to individually extend intoindividual void-spaces resulting from the removing of the pillars. 8.The method of claim 7 wherein the pillars comprise the secondsacrificial material.
 9. The method of claim 7 wherein individual of thepillars have a bottom surface and individual of the lines have a bottomsurface, the pillar-bottom surfaces and the line-bottom surfaces beingat different depths relative one another.
 10. The method of claim 9wherein the pillar-bottom surfaces are deeper than the line-bottomsurfaces.
 11. The method of claim 10 wherein the pillar-bottom surfacesare in the conductor tier.
 12. The method of claim 11 wherein thepillar-bottom surfaces are directly against the conductor material. 13.A method used in forming a memory array comprising strings of memorycells, comprising: forming a conductor tier comprising conductormaterial on a substrate; forming a lower portion of a stack that willcomprise vertically-alternating first tiers and second tiers above theconductor tier, the stack comprising laterally-spaced memory-blockregions, material of the first tiers being of different composition frommaterial of the second tiers, a lowest of the first tiers comprisingfirst sacrificial material, the second-tier material of the second tierthat is immediately-above the lowest first tier comprising undopedpolysilicon; forming horizontally-elongated troughs in the lowestportion that extend to the conductor tier; oxidizing exposed portions ofthe conductor material of the conductor tier and of the undopedpolysilicon; after the oxidizing, forming horizontally-elongated linesin the troughs that are individually betweenimmediately-laterally-adjacent of the memory-block regions; the linescomprising second sacrificial material; forming thevertically-alternating first tiers and second tiers of an upper portionof the stack above the lower portion and the lines, and formingchannel-material-string structures that extend through first tiers andthe second tiers in the upper portion to the lowest first tier in thelower portion; forming horizontally-elongated trenches into the stackthat are individually between the immediately-laterally-adjacentmemory-block regions and extend to the line there-between; removing thesecond sacrificial material of the lines through the trenches; andforming intervening material in the trenches and void-spaces left as aresult of the removing of the second sacrificial material of the lines.14. The method of claim 13 wherein individual of the lines have a bottomsurface that is in the conductor tier.
 15. The method of claim 14wherein the bottom surface is not directly against the conductormaterial.
 16. The method of claim 13 wherein the second sacrificialmaterial is of different composition from the first sacrificialmaterial, from the first-tier material that is or will be formed abovethe first sacrificial material, and from the second-tier material thatis or will be formed above the first sacrificial material.
 17. Themethod of claim 13 wherein the sacrificial material comprises metalmaterial.
 18. The method of claim 13 wherein a lowest surface of thechannel material of the channel-material-string structures is neverdirectly against any of the conductor material of the conductor tier.19. The method of claim 13 comprising: exposing the first sacrificialmaterial in the lowest first tier in the trenches; isotropically etchingthe exposed first sacrificial material from the lowest first tierthrough the trenches; after the isotropically etching, formingconductive material in the lowest first tier that directly electricallycouples together the channel material of individual of thechannel-material-string structures and the conductor material of theconductor tier; and after forming the conductive material, forming atleast a majority of the intervening material in the trenches and thevoid-spaces.
 20. A method used in forming a memory array comprisingstrings of memory cells, comprising: forming a conductor tier comprisingconductor material on a substrate; forming a lower portion of a stackthat will comprise vertically-alternating first tiers and second tiersabove the conductor tier, the stack comprising laterally-spacedmemory-block regions, material of the first tiers being of differentcomposition from material of the second tiers, a lowest of the firsttiers comprising first sacrificial material, the second-tier material ofthe second tier that is immediately-above the lowest first tiercomprising undoped polysilicon; forming horizontally-elongated troughsin the lowest portion that extend to the conductor tier; laterallyrecessing the undoped polysilicon to form laterally-opposed recesseslongitudinally-along individual of the troughs; after the recessing,forming horizontally-elongated lines in the troughs that areindividually between immediately-laterally-adjacent of the memory-blockregions, the lines individually comprising laterally-opposingprojections longitudinally-there-along that are in the laterally-opposedrecesses; the lines comprising second sacrificial material; forming thevertically-alternating first tiers and second tiers of an upper portionof the stack above the lower portion and the lines, and formingchannel-material-string structures that extend through first tiers andthe second tiers in the upper portion to the lowest first tier in thelower portion; forming horizontally-elongated trenches into the stackthat are individually between the immediately-laterally-adjacentmemory-block regions and extend to the line there-between; removing thesecond sacrificial material of the lines through the trenches; andforming intervening material in the trenches and void-spaces left as aresult of the removing of the second sacrificial material of the lines.21. The method of claim 20 wherein individual of the lines have a bottomsurface that is in the conductor tier.
 22. The method of claim 21wherein the second sacrificial material is of different composition fromthe first sacrificial material, from the first-tier material that is orwill be formed above the first sacrificial material, and from thesecond-tier material that is or will be formed above the firstsacrificial material.
 23. The method of claim 21 wherein the linesindividually comprise laterally-opposing projectionslongitudinally-there-along that are in the conductor tier.
 24. Themethod of claim 20 comprising: forming pillars in the lower portionprior to forming the upper portion, the pillars individually beinghorizontally-located where individual of the channel-material-stringstructures will be formed; and removing the pillars prior to forming thechannel-material-string structures; and forming thechannel-material-string structures to individually extend intoindividual void-spaces resulting from the removing of the pillars. 25.The method of claim 24 wherein the pillars comprise the secondsacrificial material.
 26. The method of claim 20 comprising: exposingthe first sacrificial material in the lowest first tier in the trenches;isotropically etching the exposed first sacrificial material from thelowest first tier through the trenches; after the isotropically etching,forming conductive material in the lowest first tier that directlyelectrically couples together the channel material of individual of thechannel-material-string structures and the conductor material of theconductor tier; and after forming the conductive material, forming atleast a majority of the intervening material in the trenches and thevoid-spaces.